Modification of Cotton and Leather Surfaces Using Cold Atmospheric Pressure Plasma and TiO2-SiO2-Reduced Graphene Oxide Nanopowders

Surface modification of textile fabrics and leathers is very versatile and allows the products quality improvement. In this work, cotton and leather substrates were pre-treated with cold atmospheric pressure plasma (CAPP) and further coated with TiO₂-SiO₂-reduced graphene oxide composites in dispersion form. By using a Taguchi scheme, this research evaluated the effect of three significant parameters, i.e., the pre-treatment with CAPP, organic dispersion coating and TiO₂-SiO₂-reduced graphene oxide (TS/GR) composites, that may affect the morpho-structural properties and photocatalytic activity of modified cotton and leather surfaces. The characteristics of cotton/leather surfaces were evaluated by morphological, structural, optical and self-cleaning ability using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), X-ray powder diffraction (XRD), attenuated total reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) and UV-Vis spectroscopy. The self-cleaning performance of the obtained cotton and leather samples was evaluated by photocatalytic discoloration of berry juice surface stains under UV light irradiation for 12 h. The successfulness of coating formulations was proven by the SEM analysis and UV-Vis spectroscopy. The XRD patterns and ATR-FTIR spectra revealed the cellulose and collagen structures as dominant components of cotton and leather substrates. The CAPP treatment did not damage the cotton and leather structures. The photocatalytic results highlighted the potential of TiO₂-SiO₂-reduced graphene oxide composites in organic dispersion media, as coating formulations, for further use in the fabrication of innovative self-cleaning photocatalytic cotton and leather products.

Facile deposition of biogenic silver nanoparticles on porous alumina discs, an efficient antimicrobial, antibiofilm, and antifouling strategy for functional contact surfaces

Surface modification is an emerging strategy for the design of contact materials. Fabricated alumina discs were functionalized by deposition of biogenic silver nanoparticles. The surfaces were characterized for physico-chemical, antibacterial and antibiofilm properties against microbial pathogens. The surface demonstrated improved hydrophobicity and a surface silver nanoparticle content of 6.4 w%. A reduction of more than 99.9% in CFU mL^-i was observed against the Gram-positive and Gram-negative bacteria tested, with >90% reduction of the fungal isolate. After 4 h, microbial adhesion was reduced by >99.9 and 90% for Escherichia coli and Staphylococcus aureus, respectively. Scanning electron micrographs further revealed a biofilm reduction. Cell viability tests indicated a bioincompatibility higher than 80% with Caco-2 and HaCaT cell lines after 48 h contact. The results suggest that deposition of biogenic silver nanoparticles on the surface of contact materials could be employed as a strategy to prevent biofilm formation.

Microscopic Image Segmentation and Morphological Characterization of Novel Chitosan/Silica Nanoparticle/Nisin Films Using Antimicrobial Technique for Blueberry Preservation

In the current work, the characterization of novel chitosan/silica nanoparticle/nisin films with the addition of nisin as an antimicrobial technique for blueberry preservation during storage is investigated. Chitosan/Silica Nanoparticle/N (CH-SN-N) films presented a stable suspension as the surface loads (45.9 mV) and the distribution was considered broad (0.62). The result shows that the pH value was increased gradually with the addition of nisin to 4.12, while the turbidity was the highest at 0.39. The content of the insoluble matter and contact angle were the highest for the Chitosan/Silica Nanoparticle (CH-SN) film at 5.68%. The use of nano-materials in chitosan films decreased the material ductility, reduced the tensile strength and elongation-at-break of the membrane. The coated blueberries with Chitosan/Silica Nanoparticle/N films reported the lowest microbial contamination counts at 2.82 log CFU/g followed by Chitosan/Silica Nanoparticle at 3.73 and 3.58 log CFU/g for the aerobic bacteria, molds, and yeasts population, respectively. It was observed that (CH) film extracted 94 regions with an average size of 449.10, at the same time (CH-SN) film extracted 169 regions with an average size of 130.53. The (CH-SN-N) film presented the best result at 5.19%. It could be observed that the size of the total region of the fruit for the (CH) case was the smallest (1663 pixels), which implied that the fruit lost moisture content. As a conclusion, (CH-SN-N) film is recommended for blueberry preservation to prolong the shelf-life during storage.